1. Field of the Invention
The present invention relates to a telecommunications switch and in particular to a telecommunications switching system for use on a single PSTN line for terminating calls at a plurality or multiplicity of specified destination instruments.
2. Related Art
It is often the case that a telephone line representing a single telephone number is shared by several telephone instruments at one destination. In a commercial environment small exchange switching capability can be provided such that either an additional digit or automatic switching can direct calls to different telephone instruments for different persons or purposes. This may require substantial wiring and heavy investment in equipment and/or communication network capabilities.
In domestic situations or for small businesses for example, it is common to run a single loop of, say, four wires to connect a number of telephone sockets in parallel. Thus any incoming call will cause all connected telephone instruments on the loop to activate. Providing additional telephone lines is expensive for the customer and inefficient for the network operator and may cause difficulty where a single originating call is passed among members of the same family. As an alternative a small switch would require additional digits to be transmitted through the network to select the destination telephone. Such transmission may not be possible across the telephone network until the destination line has answered a ringing signal or else the network operator may not cause connection of a speech path.